1. Field of the Invention
The present invention relates generally to mechanical-electrical connectors, and, more specifically, the present invention relates to a bolted mechanical connector for continuously wound electrical machines.
2. Description of the Background
Electrical machines such as generators and motors (collectively “machines”) basically consist of current-carrying electrical conductors assembled in slots in iron cores. To construct a practical machine, these electrical conductors must be connected together or “networked” to form functional electric circuits. The interconnection of segments of these electrical circuits may take on many different forms.
Typically, small to medium-sized machines use simple crimp-type hardware, brazing, or soldered joints to produce the connections required to form the circuits. These are relatively simple joint problems which are solved with a permanent or semi-permanent joint solution.
Generally speaking, the required complexity of the conductors, circuits, and connections are determined by the type, size, or rating of the particular motor or generator. Essentially, the larger the machine, the more complex the joint configuration and the conductor system geometry become. For example, as the size of the machine increases, the individual slot conductor, referred to here as a conductor bar, becomes a system of several individually insulated conductor strands in parallel within the single conductor bar.
FIG. 4 depicts a typical conductor bar 300 with eight individual insulated conductors 305 surrounded by an orientation would be used to form four “conductor-pairs” 320 (each one represented by a row in FIG. 4), that may each be at the same or a different electrical potential. The increased conductor complexity of these larger machines generates requirements for a more complicated connector to maintain the integrity of separations of the individual insulated strands within each conductor bar.
Small machines with round, single-piece stator cores utilize electrical conductor circuit connectors that reside within a single one-piece stator. Most, if not all electrical connections can be, and are traditionally, made in the factory. However, larger continuously wound electrical machines, like “water wheel generators” and long linear motors, are fabricated in and transported from the factory to the field erection site (or any site at which they are subsequently put together) in several segments or sections. The largest or longest length that can be transported (often determined by truck size or load weight limitations) will determine the length or size of each stator section. Longer, larger motors require a greater number of sections. As described in more detail below and as used as an exemplary machine for which to describe the present invention, FIGS. 1 and 2 depict a two-section stator continuously wound linear motor with required interconnections both before (FIG. 1) and after assembly, before electrical connection (FIG. 2).
This type of motor interface requires reliable, efficient conductor connections between each conductor of each successive stator section made at the assembly installation site. In all machines, efficient electrical joint design is required. This design effort entails maximizing the efficiency of the use of available space by minimizing the size of the connector. The connector design must include features to minimize the size, weight, and installation time.
As a partial solution, in applications not requiring ease of maintainability, minimization of field assembly time, or rapid “spare section” replacement, the electrical connection between successive stator conductors can be accomplished by making the circuit connections using weld, braze, or solder metals joining, followed by applying the required strand and outer insulation by hand. A second method sometimes used is to “bridge the interface” between sections by shipping the sections with empty slots adjacent to the section-to-section interfaces and filling these slots with field-wound full diamond coils. This method also requires “scarce craft skills” (expert knowledge and training) to wind the coils in the empty slots and complete the other required connection tasks.
Both of these traditional methods suffer from undesired characteristics including: limited maintainability, complicated refurbishment of spare part replacement, and required scarce craft skills to perform the connection work. Reliability of work performed out of the factory environment can also add unknown risks to equipment performance.
As such, there is a need in the art to provide a mechanical-electrical connector for these large, multi-sectioned stator machines that facilitates ease of assembly and replacement at the installation site, while meeting the desired electrical and mechanical specifications set forth for the machine. The present invention, in at least one preferred embodiment, addresses one or more of the above-described and other limitations to prior art systems.